Recommendations please for good, affordable pre-amp for system?

I just picked up a Bryston 11b (same family as the 0.5b, but with more features).  It is replacing a Pass DIY B1 buffer which "pani" suggested.  I also have an Aikido tube preamp I purchased on Agon.  All of the above were purchased for sub-$400.  I'm running a Belles 400 power amp and Klipsch Fortes.

All three preamps sound good.  I was running the Pass over the Aikido because the sound was cleaner and to my ear, more involving.  The Aikido has more euphonics and texture, but to the point of distracting me from enjoying the music itself.  It was more natural to toe-tap with the Pass than it was with the Aikido.

With the Bryston, I'm getting a more pleasing form factor, a nicer (for me, at least) volume setup and a built-in phono stage.  I didn't do extensive side-by-side testing, but I believe the Bryston is more similar to the Pass than it is to the Aikido.

If you have a limited budget, I don't think it's a bad thing at all to buy a 0.5B and use it until you have more funds to upgrade.  If you buy well, you'll at least break even, as Brystons hold their value well.

There are lots of opinions and there are some people who hear more things than others and people who prefer some sound personalities to others.  No one here is going to be able to tell you which preamp work best with your amp, speakers, sources, etc. without guessing or without putting their personal tastes into your system.

You have some expensive, demanding speakers.  You got a well-respected amp.  If you bought a $300-500 Bryston preamp, you might love it, you might not.  But just because someone tells you that tubes add warmth doesn't mean that warmth is necessarily a good thing or that tubes are better.  My Aikido preamp is not a high-end tube preamp, but it does add a certain sound personality.  I went back and forth between it and the Pass endlessly before settling on the Pass.  I may go back to the tube pre one day, but for now, I'm perfectly happy with a simple, easy-to-use solid state setup.

Based on how you've been in this thread, I suspect you are at the beginning of months or years of buying, trying, selling, trading, building.